Scientists Identify Weakness in Staphylococcus Aureus Bacteria

Scientists at University of Geneva (UNIGE) have identified the weakness in staphylococcus aureus that can help in treating people infected by this difficult-to-treat bacterium.

The bacterium has the ability to develop in highly variable environmental conditions. Known also as Golden staph, the bacteria is an opportunistic one that is capable of adapting to highly variable environment conditions. It can be found in the nostrils of 25 to 30% of the population. It can take advantage of a drop in immunity or a surgical operation to trigger an infection. It develops resistance to antibiotic drugs, which often makes it difficult to treat.
In cases where the helicase CshA is absent, the bacteria could no longer form colonies in a changed environment especially when temperature drops below 25 degree centigrade. The presence of this helicase is required to synthesize new proteins that are more suitable and stop production of others not use.
The Geneva-based biologists undertook a series of experiments designed to improve our understanding of the link between golden staph’s sensitivity to cold, the degradation of the RNA and the adaptation capacity. They discovered that the same helicase is probably also required in another physiological process, namely the synthesis of fatty acids, which are the constituents of bacterial membranes. “Using cultured golden staph stripped of helicases, we succeeded in isolating 82 gene mutations (appearing spontaneously in many different bacteria), which meant that their holders regained the ability to form colonies at 25°C,” continues Vanessa Khemici, a researcher in Patrick Linder’s laboratory and the article’s first author. “We identified almost all the affected genes, and no less than two thirds of them are involved in the fatty acid synthesis.”

The findings also helped the researchers understand that the lack of the helicase has the effect of deregulating the fatty acid synthesis and decreasing the flexibility of the membrane when the temperature drops. This prevents the membrane from fulfilling its functions properly and the bacterium from growing. In a second step, each of the 82 mutations succeeded in its own way in restoring the initial balance by acting on the different genetic levers involved in fatty acid synthesis. 
“A section of the scientific community supports the idea that a future treatment against staphylococcus will involve a drug capable of inhibiting fatty acid synthesis,” notes Professor Linder, “but there is a controversy about it because some studies contradict this point of view.” The results of the Geneva scientists do not provide a clear-cut answer or make it possible to directly develop a drug against these bacteria.
Nevertheless, they fit into this context and provide a better understanding of golden staph’s fundamental mechanisms. The discovery of this unprecedented link between the fluidity of the membrane and adaptation to environmental change represents an important step in the fight against the bacterium.